Distributed architecture for a base station transceiver subsystem having a radio unit that is remotely programmable

ABSTRACT

A telecommunication base station transceiver subsystem that can be easily configured to provide single or multi-carrier frequency service. The base station is divided into a main unit and a radio unit such that the radio unit is positioned proximate to the antennas and the main unit is remotely located from the radio unit. A single base station transceiver can provide service via multiple wireless protocols, such as CDMA, TDMA, GSM or Analog. The base station transceiver .can also operate on various transmit/receive frequencies as well as variable transmit power settings. Furthermore, the base station transceiver can be reprogrammed, reconfigured and/or statused by a network operations center.

CROSS REFERENCE TO RELATED APPLICATIONS

This application, is a continuation-in-part of 09/149,168, filed Sep. 8,1998, which claims the benefit of U.S. Provisional Application No.60/058,228, filed Sep. 9, 1997.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention generally relates to wireless communicationsystems and, more particularly, to base station transceiver subsystemsused in a Code Division Multiple Access (CDMA) network or other digitaland analog telecommunication systems.

2. Description of Related Art

FIG. 1 (prior art) is a block-flow diagram which graphically representsa wireless communication system. From FIG. 1 it is seen that a basicwireless communication system comprises a mobile station 10, a basestation 20, a reverse link 30, which represents the electromagnetic wavecommunication link transmitted from mobile station 10 to base station20, and a forward link 40 which represents the electromagnetic wavecommunication link transmitted from base station 20 to mobile station10.

FIG. 2 (prior art) shows a cell grid and cell sites. In a wirelesscommunication system based on the general cellular principle, a servicearea 49 is divided geographically, into a number of small areas 50, 52,54, 56 called “cells.” In each cell there is a cell site 58, 60, 62, 64where radio equipment known as a Base Station Transceiver Subsystem(BTS) is installed. Multiple cell layouts such as macro cells, microcells, and Pico cells can be provided within a particular geographicalarea to effect hierarchical coverage (where macro cells provide thelargest coverage and Pico cells the smallest). Pico cells may be used toprovide coverage,inside buildings, to cover a special area (campus,stadium, airport and shopping mall), to temporarily cover for specialevents or areas hit by natural disasters, to cover outlying remotelocations, to supplement macro or mini cells with hole-filling, or toenhance the capacity of hot spots. FIG. 3 (prior art) is a block diagramof a wireless system network connected to a land line Public SwitchedTelephone Network (PSTN) 68. As shown in FIG. 3, a BTS 66 provides alink to mobile subscribers or (mobile stations) 10. Each BTS 66typically may include two or more antennas 67, which may be omniantennas or directional antennas. Omni antenna configurations provide360° of coverage, whereas directional antennas provide less than 360° ofcoverage across an area known as a sector. For example, there may betwo, three or more sectors in a typical directional configuration suchthat each sector of a two sector configuration generally provides 180°of coverage and each sector of a three sector configuration generallyprovides 120° of coverage, etc. For satisfactory reception andtransmission, each sector typically requires at least two antennas fordiversity reception.

Continuing with the description of FIG. 3, each BTS 66 is coupled to aBase Station Controller (BSC) 70 (multiple BTSs 66 may be coupled to asingle BSC 70). Likewise, each BSC 70 is coupled to a Mobile SwitchingCenter (MSC) 72 and the MSC 72 is in turn coupled to a PSTN 68.

FIG. 4 (prior art) is a functional block diagram of a BTS. As shown inFIG. 4, a conventional BTS 66 typically comprises four major functionalblocks for each sector of coverage: an RF front-end 74, a plurality oftransceivers 76, a plurality of modem processors 78, and a controller80. Controller 80 interfaces with a BSC 70 over a T1 or E1 line 81, andthe RF front-end 74 is connected to the antennas 67 which are typicallymounted at the top of a tower or pole 82 as represented in FIG. 5 (priorart), where FIG. 5 illustrates an outdoor and ground based BTS coupledto a tower topped mounted antenna.

In a typical system, the four major functional blocks of the BTS 66,shown in FIG. 4, are contained in one physical cabinet or housing whichis in close proximity to a pole (or tower) 82 at ground level. Longcoaxial cables 84 are then run to the top of the pole 82 where theantennas 67 are mounted. The cable length typically varies from 50 to200 feet, depending on various installation scenarios. Cables of theselengths suffer from undesirable power losses. Accordingly, thick coaxialcable diameters of approximately ¾ to 1½ inches are used to minimize thecable power loss, which is typically about 2 to 4 dB. Minimizing thesepower losses is important because such losses in the cables degrade thereceiver sensitivity and reduce transmission power.

FIG. 5 depicts a prior art BTS unit 66 connected via a long length ofcable 84 to an antenna 67 at the top of a supporting structure 82. FIG.6 (prior art) is a block diagram of yet another known BTS architecturewhere a tower top mounted RF front-end module consists of a Low NoiseAmp (LNA) and a Power Amp (PA) 74 (hereinafter LNA/PA unit 74). Thecable power loss in this architecture is not as critical as in theprevious mentioned architecture because the power loss can be made upwith additional amplification. However, there is still a need to userather thick cables due to the signals between the LNA/PA unit 74 andthe transceiver 76 in the BTS 66 are high frequency/radio-frequency (RF)signals. Other problems are associated with transmitted RF signalsbetween the LNA/PA unit 74 and the BTS 66, such as power losses, systemnoise, and mechanical clutter. Furthermore additional complex circuitryeither or both in the RF front-end module and the transceiver may berequired to automatically compensate for the wide range of cable lossesthat arise in different installation scenarios due to varying cablelengths. Such problems get more severe as the operating RF Frequenciesare allocated in the increasingly higher frequency bands. This is thecase for personal communications systems.

In other words, as the length of a cable 84 increases, or as thefrequency transmitted through a cable 84 increases, power losses betweenthe LNA/PA unit 74 and the BTS 66 increase. Thus, the long cables 84used to connect the LNA/PA unit 74 to the BTSs 66 (often in excess of150 feet, sometimes even exceeding 300 feet) introduce large powerlosses. For example, a 100 W power amplifier in a base stationtransceiver unit transmits only 50 W of power at the antenna when thereis a 3 dB loss in the cable. Power losses in the cable work againstreception as well, reducing the ability of the receiver to detectreceived signals. Also, with Personal Communication Systems (PCS)operating at high frequencies, the power loss in the cable 84 runningbetween the LNA/PA unit 74 and the transceiver 76 in the BTS 66increases. Thus, RF cable losses incurred on both the transmit andreceive paths result in poorer than desired transmission efficiency andlower than desired receiver sensitivity, making the use of relativelythick (high conductance) coaxial cables necessary to minimize loss.

Generally, in a wireless environment, wherein radio frequencies aretransmitted through air, interferences are inevitable. That is, unless atransmitting antenna is directly in the line-of-site of the receivingantenna and no obstacles, such as trees, buildings, rock formations,water towers, etc., are in the way, then reflections will cause fadingand multipath signals. In order to minimize the effects of fading andmultipath, diversity receivers can be used increase the carrier-to-noiseratio (and/or Eb/No. A diversity receiver requires its own antenna.Thus, for each transmission frequency two antennas are used on thereceiving side. One antenna is a transmit/receive antenna and the secondantenna is used for a diversity receiver which is utilized to overcomesome of the fading and multi-path problems.

In some cell sites, where the communication capacity is high, there is aneed to transmit more than one RF carrier signal. The transmission ofmultiple RF carriers per sector requires a corresponding number oftransmit antennas per sector. Additional receiving antennas are alsorequired especially if diversity receivers are utilized in the system.Increasing the number of antennas creates an “eye-sore” for the publicand is not desirable.

A conventional technique for reducing the number of transmit antennasrequired for multiple RF carrier transmission are shown in FIGS. 7 and8.

In FIG. 7 (prior art) the carriers are combined with a high powercombiner. In FIG. 8 (prior art) the carriers are combined at low powerand then the combined signal is amplified with a multi-carrier poweramplifier.

Neither design is suitable for use in a compact BTS system due to highpower loss in the combiners and the inability to provide diversityreception.

What is needed is a compact BTS system that can be adapted to handlemultiple transmit and receive frequencies, multiple sectorconfigurations, multiple wireless communication protocols and be able totransmit signals at a variety of power levels for different types ofcells (e.g. macro-, micro-, pico-), without increasing the number ofantennas significantly or substantially decreasing the overallperformance of the system.

SUMMARY OF THE INVENTION

The present invention provides a BTS wherein a radio unit (RU) islocated proximate to the antenna mounting location. A main unit (MU) isconnected to and remotely located from the RU. One or more antennas arecoupled to the RU. There can be a plurality of RUs connected to a singleMU. The plurality of RUs may operate on the same or differentfrequencies, the same or different transmit power, the same or differentwireless communication protocols.

An exemplary embodiment of the present invention minimizes the number ofantennas required for multiple frequency, multiple communicationprotocol, or variable transmit power BTS system.

Another exemplary BTS system allows for two RUs to be connected togetherto thereby increase the number of operating frequencies, orcommunication protocols, while maintaining transmission power levelwithout increasing the number of antennas.

Another exemplary embodiment of the present invention is to increasecall capacity of a BTS without increasing the number of antennas for acell, thereby minimizing the cost of increasing the call capacity.

Another exemplary embodiment of the present invention transmits andreceives two frequencies or wireless protocols with two antennas andmaintains diversity reception. The diversity receiver helps to minimizethe effect of fading and multipath.

There are many advantages to this exemplary architecture and some ofthem may be as follows:

A compact size RU is provided which can be easily mounted close to theantennas, whereby cable loss is virtually eliminated. Cable lossesdegrade the receiver sensitivity and reduce the transmit power. Thepresent invention, thus, allows for a relatively low power PA andprovides a transmit power level equivalent to a higher power PA used ina prior art BTS.

The inclusion of the transceiver in the RU allows for a lower frequencyinterface rather than an RF interface typically used in prior arts, tothe MU. The lower frequency interfaces yield lower cable losses, thusallowing the use of inexpensive and small diameter interconnect cablesbetween the RUs and the MU.

The separation of RF elements and dependent elements thereof, also,result in easier adaption of the BTS design to support different RFoperating environments or conditions, as in different frequency bandsand different transmission power levels, as only the RU needs to bemodified, while the same MU is used. This also results in a compact sizeMU for ease of handling and mounting. This is because less space andweight are required without RF elements installed and, at the same time,less heat is generated in the MU requiring cooling.

This architectures allows a wireless communication provider to provideservice via a variety of wireless protocols without the need for adifferent BTS for each protocol.

This architecture also allows the BTS to be configured to support eitheromni or sector operations, or to upgrade from omni to sector operationsas the traffic demand goes up. This is especially important in CDMAsystems where softer handoffs need to be supported between the sectors.For an omni configuration, only one RU is needed. For two or threesector configurations, two and three RUs are needed, respectively. Thethree RUs can be operated on the same frequency in a three sectorconfiguration or at different frequencies in a three carrier omniconfiguration.

The present invention also allows the connectivity of another set ofthree RUs connected to its own MU to the same antennas without the useof a combiner.

By locating the transceiver module in the RU, only low frequency signalsneed be passed from the transceiver module and the MU. On the receiveside, the transceiver module converts a high frequency signal to a lowfrequency signal, and on the transmit side, the transceiver moduleconverts a low frequency signal from the MU to a high frequency signalfor transmission. Thus, only low frequency signals are passed betweenthe RU and MU, minimizing power loss in the cables connecting the twounits. This results in the ability to use smaller diameter; less costlycables.

Another advantage to removing the transceiver subsystem from the MU isthat the resulting MU is physically much smaller in size and weighsless. This translates into easier installation and maintenance, as wellas into flexibility in meeting the technical demands of a challengingoperating assignment or challenging environmental considerations. Inaddition, smaller size and lighter weight BTSs are especiallyadvantageous for Pico-cell applications or micro-cell applications wherea greater number of BTSs are required than are needed for macro cellimplementations.

Since the entire transmit functionality is contained in the RU, the RUreceives only a baseband signal for transmitted data and does all of theup-conversion and amplification at the RU. This eliminates the need forsending RF signals up to the RU, thus allowing the RU to operate at ahigher efficiency than a unit in which the RF signal must travel thelength of the pole.

Up-conversion is done in the RU, thus, direct modulation reduces thecomplexity of the transmit signal line, and provides a significant costreduction over systems that run a transmit signal up the pole and thenup-convert again to RF. Far less RF components are required in thepresent invention than in the prior art.

Output power calibration can be performed at the factory and the RU canbe programmed for usage with any MU. The RU will store full-powersettings, as well as reduced power settings, in local memory—thusenabling cell size adjustment from the RU, instead of at the BTS.

Wilting and blossoming attenuation can be accomplished in the RU ratherthan in the BTS. Also, output power detection is performed in the RUand, more important, can be used to verify the integrity of the entiresignal transit path. Previously, in units where the PA is mounted on thepole, the output power attenuation could be detected, but the operatorcould not determine if the problem was in the PA module or the MU.

System upgrades can be accomplished more easily as entire RUs or MUs canbe, replaced. In addition, because like elements are configuredtogether, board or device level upgrades are also more easilyaccomplished than with traditional BTS units.

These and other advantages of the present invention will become apparentto one of ordinary skill in the art after consideration of the figuresand detailed description which follows hereinafter.

BRIEF DESCRIPTION OF THE DRAWING

A more complete understanding of the method and to apparatus of thepresent invention may be had by reference to the following DetailedDescription when taken in conjunction with the accompanying Drawingswherein:

FIG. 1 (prior art) depicts a wireless communication system architecture;

FIG. 2 (prior art) is a graphical representation of a cell grid and cellsites.

FIG. 3 (prior art) is a block diagram of a base station system (BTS)shown connected to a land-line PSTN;

FIG. 4 (prior art) is a functional block diagram of a BTS;

FIG. 5 (prior art) is an illustration of a ground based BTS coupled to atower top mounted antenna;

FIG. 6 (prior art) is a block diagram of a tower top configuration;

FIG. 7 (prior art) is a block diagram illustrating the combiner methodfor using one antenna to support multiple transceivers;

FIG. 8 (prior art) is a block diagrams illustrating thecombiner/multi-carrier method for using one antenna to support multipletransceivers;

FIG. 9 illustrates a base station system according to an embodiment ofthe present invention coupled to a pole-mounted antenna;

FIG. 10 is a block diagram illustrating a base station transceiversubsystem architecture according to an embodiment of the presentinvention for an omni configuration;

FIG. 11 is a block diagram illustrating a base station transceiversubsystem architecture according to an embodiment of the presentinvention for a three sector configuration;

FIG. 12 is a functional block diagrams of a BTS architecture accordingto an embodiment of the present invention, with selected subsystemsshown;

FIG. 13 is a modular level block diagram of an exemplary BTS;

FIG. 14 depicts an exemplary block diagram of a single or multiplefrequency, 3-sector embodiment of the present invention;

FIG. 15 depicts an exemplary block diagram of a dual frequency,3-sector, antenna sharing embodiment of the present invention;

FIG. 16 depicts a block schematic of the duplex and diversity receivingchannels of an exemplary PRU; and

FIGS. 17(a-e) depicts a plurality of exemplary embodiment configurationsof the present invention.

DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EXEMPLARY EMBODIMENTS OFTHE PRESENT INVENTION

In the description which follows, exemplary preferred embodiments of theinvention are described for a Pico base station transceiver subsystemarchitecture. However, it will be understood that the present inventionmay be applied to any base station transceiver subsystem architecture ina wireless communication system, including, but not limited to, macroand micro base station transceiver subsystems.

FIG. 9 illustrates the basic idea underlying a base station transceiversubsystem (BTS) architecture according to an exemplary embodiment of thepresent invention—the BTS is separated into two units, the Pico-BTSRadio Unit 110 and the Pico-BTS Main Unit 105. In the exemplary systemillustrated in FIG. 9, a Pico-BTS comprises the Pico-BTS architecture100 which is divided into the Pico-BTS Main Unit (“Main Unit System,”PMU, or MU) 105 which may be located, as shown, at the base of a pole,tower, or other support structure 115, and the Pico-BTS Radio Unit(“Radio Unit System,” PRU or RU) 110, which transmits and receivessignals through at least one pole-mounted antenna 120, and communicateswith the PMU 105 via a plurality of wires 122 which may include a coaxcable.

An embodiment of the present invention is illustrated in a high-levelblock diagram as an omni configuration in FIG. 10. PRU 110 can bedistally connected to the PMU via the wires or cables 122. The distanceor separation between the PRU 110 and the PMU 105 can be more than 350feet (current systems are typically separated by about 150 feet). Thisis adequate since the PMU 105 is designed to be placed at the bottom ofa tower building, pole or other supporting structure 115 and the PRU 110is to be placed at the top near the antenna(s). To transmit and receivesignals, the PRU 110 is shown coupled to one, but typically is coupledto at least two, tower top mounted antennas 120.

The wires or cables 122 can include optical cabling between the PMU 105and the PRU 110. Optical cabling will increase the distance allowablebetween the PMU and RMU because an optical signal will be less lossythan an electric signal in, for example, la coaxial cable.

FIG. 11 illustrates a BTS architecture according to an exemplaryembodiment of the present invention for a three sector configuration.Note that the hardware systems which are required to be duplicated areonly duplicated in the PRU 110. Thus, the PMU is capable of interfacingwith 1, 2, 3 or potentially more PRU's.

FIG. 12 is a block diagram illustrating exemplary elements of the PRU110 and the PMU 105. As seen the PRU 110 is composed of transceivermodule 155, which is couple to the antenna interface assembly 160. Theantenna interface assembly 160 is coupled to the antennas 120.Controller circuitry 126 controls the antenna interface 160 andtransceiver 155 portions of the PRU 110. The con roller circuitry cancontrol the power output level of the antenna, the carrier frequencyused to modulate the communication signal, or can support differentcontrol mechanism control mechanisms required by different communicationprotocols employed by the PRU 110.

The PRU 110 is coupled to the PMU 105 through a set of cables 122 whichterminate in the PMU 105 at the Transmit and Receive interface 135 (T/Rinterface), which is coupled to the channel elements 130. The channelelements 130 are where a CDMA signal or other communication protocols ismodulated and demodulated. There are a variety of protocols that couldbe supported by a single PMU and PRU combination. Such protocolsinclude, but are not limited to CDMA, IS95 (A,B,C, etc.), Wide BandCDMA, IMT-200, CDMA2000, TDMA IS-136, GSM, AMPS analog, NAMPS analog,paging protocols, short message service protocols, and any othercellular or PCS protocols. The PMU 105 may also contain a globalpositioning receiver 140 which provides accurate clock and frequencysignals to a main controller module 125, the channel elements 130, theT/R interface 135, and the PRU(s). Also within the PMU 105 is a powersystem 145, and a temperature control subsystem 150.

FIG. 13 provides additional detail of the PRU 110 and PMU 105subsystems. As shown in FIG. 13, each PRU 110 essentially comprisesthree modules: a transceiver module 155 (XCVR), antenna interface module160 (AIF) and controller circuitry 126. These modules, however, can becombined into one or more than one module. Accordingly, the antennainterface module 160 may include a transmit power amplifier (PA) whichamplifies the signal to a level required for desired cell coverage, twolow-noise amplifiers (LNA-not shown) for amplifying received signals tomaximize receiver sensitivity, a duplexer module for transmitting andreceiving signals to and from a single antenna, and a receiver filter(Rx). The transceiver module 155 may include synthesizer circuitry,transmitter circuitry, and two receiver circuits (it is common to referto a system's transmitter and receiver circuitry collectively as a“transceiver”).

The PRU 110 also includes a controller portion 126 which includes amicroprocessor and non-volatile memory to store calibration data andprovide real-time temperature operating parameter compensation to thetransceiver. Thus, a mobile station or mobile simulator is not neededfor calibration, and system calibration in the field is also no longerneeded. PRU 110 preferably houses the duplexer and the receive filter ina common cavity. This is essentially three filters (two receive and onetransmit) combined into one metallic cavity. By combining the prior artduplexer cavity with the prior art diversity receive cavity, valuablespace inside the unit may be used for other circuitry and cost isfurther reduced.

In the preferred exemplary embodiment, the duplexer/receiver filtercavity of PRU 110 is designed so that the connectors on the filterprotrude directly through the cover of the unit, eliminating any coaxialcable bulkhead connectors. This approach requires fewer parts in theunit, again saving valuable space and reducing cost.

An embodiment of the present base station transceiver can provide alarge amount of flexibility to the wireless service provider. First ofall the transmit power amplifier found in the antenna interface portion160 can be controlled by the controller circuitry 126 to output variouspredetermined amounts of power. For example, the transmitter power ampof the exemplary embodiment may be able to transmit at powers rangingfrom half a Watt to as high as 30 watts or more. Different PRUs, couldbe manufactured to provide varying amounts of transmitter power. One PRUmay be designed to transmit from half Watt to 5 Watts. Another PRU maytransmit from 1 to 10 Watts. Still yet another PRU embodiment may beable to transmit from 3 to 30 Watts. The amount of output power iscontrolled by the controlling circuitry 126.

The controlling circuitry may be communicated to via the cables 122 bythe main unit 105. Thus, the output transmit power of the PRU 110 can bechanged without physical servicing of the PRU 110. Instead a controlsignal can be sent to the PRU 110 to vary the transmit power. Anadvantage of being able to actively change the transmit power of a PRUare that the traffic carried by a network of base stations in a cellularstyle communication network can be balanced. In a downtown portion of alarge city there may be a large density of customers in a relativelysmall area during daytime business hours, but may be a much smallerdensity of cellular customers in the evening or on weekends, the presentexemplary PRU 110 can be set to balance traffic during weekday businesshours by transmitting at a lower power to limit its range and pick upthe high density of customers. In the evening or on weekends it can bereconfigured to transmit at a higher power to increase the PRU's rangeand pick up calls within the lower density of customers in the area.

Another way an exemplary embodiment of the present exemplary basestation transceiver can provide additional flexibility to a serviceprovider is by providing radio units that can be either programmed orhardwired to transmit and receive at different frequencies. Being ableto transmit and receive at multiple frequencies is useful for manyreasons. Each additional transmit and receive frequency increases thecapacity of the BTS. Utilizing two frequencies doubles the capacity andutilizing three frequencies triples the capacity. Each PRU 110 that isin communication with a PMU 105 can be programmed or hardwired totransmit at a different frequency.

Furthermore, by operating at different frequencies, interference betweensectors, adjacent cells and other wireless communication carriers can beminimized. Also, frequency interference between different protocols canbe minimized.

The PRU 110 can also be designed to transmit and receive variousdifferent protocols. Furthermore, PRUs utilizing different protocols canall be connected to the same PMU 105. Such various protocols include,but are not limited to CDMA, Wide Band CDMA, CDMA2000, IMT-2000, TDMA,GSM, AMPS, NAMPS, Analog protocols, paging protocols, short messageservice protocols, and other digital protocols.

The PMU 105 may exercise a level of control over the PRU 110. That is,the PMU may be able to control the setting of the transmit power, thefrequency, or the protocol that the PRU 110 utilizes. The PMU 105receives a message via a wireless backbone network or other PSTNrequiring a change in the characteristics of the PRU.

As discussed above, the PMU 105 may exercise a level of control over thePRU 110 by controlling a variety of variable or programmable aspects ofthe PRU 110. Referring to FIGS. 11 and 12, there are depicted twoexemplary BTS systems 100 in accordance with controllable andprogramable aspects of the invention. In the exemplary embodiments,software can be downloaded from the PMU 105 to the PRU 100 to control,for example, the radio frequency (RF) portion of the PRU 110.Preferably, when the PRU 110 is turned on, software is downloaded to itfrom the PMU 105. Furthermore, when the PRU 110 is on and operating,updates or changes in software or control of the PRU 110 can bedownloaded from the PMU 105.

A craft, a person or operator at a Network Operations Center (notshown), can request, via a PSTN 500 or MSC 502, the version number ofthe radio unit software that is loaded into the PRU. The craft may thenverify the loaded software version against the latest available softwareto check if the PRU requires a software upgrade.

The radio unit software, when installed in the PRU and PMU, can controla wide variety of functions performed by the PRU 110 and PMU 105. Theradio unit software and data is downloaded from PMU 105 to the PRU eachtime the PRU is turned on. The radio unit software can also be upgraded,modified and downloaded to a PMU and PRU via a craft's instructions.

Although the specifics will be described in more detail below, the radiounit software can be utilized to set, among other things, thetransmission frequency of each PRU 110. In the exemplary embodiment, thefrequency can be selected from the range of A band through the F band ofthe CDMA frequency spectrum. It is understood that one of ordinary skillin the art could modify the invention to handle virtually any wirelesscommunication frequency.

The exemplary radio unit software enables the PMU 105 to control andoperate with a plurality of PRUs (three PRUs are shown) such that eachPRU may operate at different frequencies, at the same frequencies, in asector configuration, in a plurality of OMNI configurations, or anyvariation thereof.

Referring again to FIG. 11, a base station subsystem (BTS) 100 isconnected to a Base Station Manager (BSM) 504 via a BSC, a MSC 502 or aPSTN 500. The exemplary BSM 504 holds the data bases and the softwarefor downloading in a data storage device 505.

A craft, located at a network operation center, can “see” theconfiguration of at least large portions of a cellular phone system. Thecraft can reconfigure one or more BTS 100 units by turning them off(bringing them down), downloading new or changed radio unit softwarefrom the data storage device 505 to the BTS 100, resetting the BTS 100and bringing the BTS 100 back on line (bring them back up).

When software or reconfiguration data is sent at the direction of thecraft to an exemplary BTS 100, the PMU 105 first receives the softwareor reconfiguration data and then transmits the necessary information tothe associated PRU 110 via, for example, a cable bundle 122.

In an exemplary BTS 100, after the PRU 110 is reset, the PMU willdownload appropriate radio unit software or data to the PRU 110. Oncethe appropriate radio unit software or data is downloaded to the PRU110, the PRU 110 configures itself to operate in accordance with theloaded software or data.

Furthermore, while-the PRU 110 is “ON” and operational, information andcommands can be sent between the PRU and PMU. For example, the PMU 105may request the PRU 110 to provide receiver signal strength, temperatureor other status information to the PMU for analysis or for delivery tothe craft. In particular, the following commands can be sent from thePMU 105 to the PRU for the PRU to respond or reply to.

Performance Manager Commands

Start Collecting Receiver Signal Strength Indicator (RSSI)Information—With this command, the PMU 105 requests that the PRU 110 tobegin collecting signal strength or RSSI information and to provide thecollected information to the PMU 105.

Stop Collecting RSSI Information—Here the PMU 105 tells the PRU 110 tostop collecting signal strength or RSSI information.

Pico Performance Management Receiver Signal Strength Internal TimeOut—With this command, the PMU can instruct the PRU to send RSSIinformation just once or at predetermined time intervals and/or for apredetermined amount of time.

Configuration Management Commands

Configuration Initiate—This exemplary command, sent by the PMU to thePRU, tells the PRU that a configuration or new configuration needs to beinitiated.

Configuration Data—Configuration data is data that is sent from the PMUto the PRU to configure a plurality of ‘settings’ in the PRU. Theconfiguration data comprises, among other things, the radio frequencychannel number, the transmit power level setting and receiver signalstrength settings.

The receiver signal strength settings may be used to help calibrate andset the transmit power of the PRU's transmitter(s). It is noted that asthe PRU warms up, or is subjected to different operating temperatures,the actual transmitted power may drift from the set transmit power.Thus, the RSSI information can be used by the PMU to set the transmitterpower of the PRU to compensate for a change of transmitted power due totemperature fluctuations. The receiver signal strength settings can beused to attenuate or amplify the transmission frequency. The attenuationvalue can also be used to effectively stop transmission of atransmitter. There can be other configuration settings or parametersprovided with the configuration data as needed or required by the PRU.

Test Manager Commands

Receive Attenuation Control—This command from the PMU to the PRUrequests that the receiver circuitry of the PRU be tested to determinewhether the receiver signal path is working. In an exemplary embodiment,the PRU is placed into a self-test mode such that the receiverattenuation is varied and the RSSI information is provided to the PMU bythe PRU.

Transmitter Power Level Request—Here, the PMU requests that the PRUprovide the present transmit power setting. Even though the transmittermay be set at, for example, 5 watts, the transmit power will beincrementally different from 5 watts. The PMU decides, based on the settransmit power level and the RSSI information, if whether the PRU'stransmitter circuitry is working via the radio unit software.

Voltage Standing Wave Ratio Level Request—This command is sent by thePMU to the PRU to request that the PRU calculate the standing wave ratioon a transmit or receive antenna. The standing wave ratio calculationwill provide information indicating as to whether an antenna connectedto a PRU is bent, broken or disconnected.

Power Control Request—This command is used by the PMU to request thatthe PRU indicate whether the transmitter/receiver circuitry power is onor off.

Fault Management Interface Query

Alarm Configuration Request—This request made by the PMU requests thatan alarm configuration be initialized. Various predetermined operationalranges for the PRU alarms can be established. For example, the PRU canbe set to provide an alarm signal to the PMU if the temperature of thePRU is outside a predetermined range, or if a predetermined circuit,such as a receiver, transmitter, or control card fails.

Alarm Status Request—This request by the PMU requests the status of eachconfigured alarm setting in the PRU.

Fault Management Reset Request—This command sent by the PMU to the PRUrequests the PRU to go through a reset. After this command is sent bythe PMU, the PRU will have to be reconfigured. A new configuration willbe sent to the PRU via the configuration command.

Download Version Request—With this command, the PMU can require the PRUto provide software version information for the presently operatingsoftware.

Fault Management Alarm Report

Alarm Report Acknowledgment—Here the PRU initiated an alarm report byproviding an alarm signal to the PMU. The PMU replies to the PRU with analarm report acknowledgment indicating that the PMU received the alarmreport. For to example, the PRU may have determined that the transmittertemperature is too high. The PRU sent an alarm signal to the PMUindicating that the, transmitter temperature is outside of apredetermined range. The actual temperature reading may also beprovided. In response thereto, the PMU will send an alarm reportacknowledgment to the PRU.

The PRU may continue to send an alarm report to the PMU, for example,every five seconds until the PMU acknowledges that the alarm report wasreceived.

Ping

Ping—The PMU sends a ping command to the PRU on a continuous intervalbasis. For example, a ping may be sent to the PRU every three seconds.Upon receiving each ping, the PRU must return a reply signal indicatingacknowledgment of receipt of the ping. The ping is used to make surethat the data connection between the PMU and the PRU is operational andthat the software in the PRU is not in a “run away” state.

In an exemplary BTS 100, if a ping is not acknowledged by the PRU threetimes in a row, then the PMU will shut down the PRU by first attemptingto power down the transmitter(s) and second, power down the unit andreinitialize it.

Transmitter Power Level/Control

Transmit Attenuation Control—This command is sent to the PRU to controlthe amount of attenuation to apply to the transmit signal.

Transmit Power Control—This command is used to set the power output ofthe transmitter. In the preferred embodiments, the power output can begenerally set at 1, 5 or 10 watts. These output powers are adjusted bythe circuitry depending on temperature, antenna type, PRU configuration,etc.

Furthermore, it is understood that the PMU may be responding , in somecases, to commands sent from a craft via the BSC, MSC, BSM or PSTN. Thecraft may require the communication network to have differentconfigurations based on the time of day (rush hour, non-rush hour), anemergency event, a holiday, increased usage due to area populationincrease, etc. The PRU may also be responding to commands generated, notby the craft, but by any number of automated programs which monitor acellular communication network.

An exemplary BTS 100 in accordance with the present invention provides ameans for configuring, programming and communicating commands to andwith a radio unit (PRU) located to distally, but in communication with,a main unit (PMU) such that the BTS can be an integral programmableasset to a telecommunication system.

The PMU is responsible for the digital termination of a wirelessprotocol. That is, for example, the PMU handles the landline-to-CDMA orCDMA-to-landline conversion. On the other hand, the PRU receivesbaseband signals of the proper protocol from the PMU and modulates themto the appropriate radio frequency.

As illustrated in, FIGS. 12 and 13, the PMU 105 includes six functionalsubsystems: a Pico-BTS main controller card 125 (PMCC), a Pico-BTSchannel card 130 (PCC), a transmit and receive interface card 135(TRIC), a time and frequency card 140 (TFC), and a power supply assembly145 (PSA) for converting AC to DC and for distributing the DC powerthroughout the PMU 105 and the PRU 110. The temperature managementsubsystem 150 is not shown in FIGS. 12 and 13 to simplify the Figures.

In operation, the PMCC 125, which includes an external interface moduleand a communications controller module, often called a packet engine,monitors all of the cards in the BTS architecture 100 and routes trafficand signaling packets between a Base Station Controller (BSC, see FIG.3) shown) and the PCCs 130. Likewise, the TRIC 135 provides theinterfaces between the transceiver module 155 and the PCCs 130. The PCCs130 are responsible for converting landline communication informationinto the proper protocol baseband (such as CDMA) for transmission to aPRU 110 via a cable 122. The TRIC 135 provides the connectivity to thePRU 110 through interconnect cables 122.

Baseband analog signals and intermediate frequency (IF) signals offrequency range lower than that of the over-the-air radio frequency (RF)(e.g. of about 1 KHz to about 700 MHZ) are propagated in cables 122connecting PMU 105 with PRU 110. One preferred IF frequency for thereceive link is 239 MHZ with a 1.26 MHZ bandwidth and with an analogbase band for the transmit link. The advantage of this approach is thatthe transmit and receive signals can be duplexed and sent through astandard, inexpensive RG-58 coaxial cable. Other signals to be carriedbetween the units include 48V power, a 10 MHZ reference, and RS-422control lines.

The separation of the PRU 110 and the PMU 105 allows the PRU 110 to beinstalled close to the antennas 120. Since in practice power losses inthe antenna cable degrade receiver sensitivity and reduce the transmitpower at a 1:1 ratio (dB per dB), locating the PRU 110 in closeproximity to the antenna 120 maximizes the performance of the BTS 100.The location of the PRU also reduces power and signal losses through acable and thereby may save energy and increase efficiency.

It is worth noting that all wires and coaxial cables may be bundled intoa single polymer jacket. Thus, a single multi-wire/coaxial connector isused at both ends of the cable. The resulting cable is typically builtas a unitary item which provides easy of installation and repair in thefield. Thus, the cable diameter may easily be kept under 0.75 inches,providing easy installation in the field, as well as in an indoorapplication (which require turning corners).

Coaxial cables coming into PRU 110 are transformer coupled to thetransceiver, which eliminates the possibility of ground loops (and theircorresponding ground noise), and ensures that the PRU 110 can be placedup to and in excess of 150 feet away from PMU 105. In addition, if thePRU 110 is connected to a pole or other conductive structure which isgrounded, there will be no system performance degradation due to noisecoupling. Power, at 24 or 48 VDC or an AC voltage, is sent to the towertop with a separate return. This provides less power loss in the powerwires, making the system more efficient.

The signals carried by the cable 122 between PMU 105 and PRU 110 operatemost efficiently over a range of about 1 KHz to 240 MHZ. This results inlow signal attenuation, even when using thin, low cost cables.

In certain environments wherein heavy communication traffic isprevalent, it may be advantageous to connect two PRUs together and usetwo carrier frequencies. The exemplary embodiment can connect two PRUstogether and transmit and receive two carrier frequencies with minimaldegradation of signal quality and without increasing the number ofantennas required. This is advantageous because the public is notsubjected to additional potentially unsightly antenna yet acquiresadditional service from the PRU via an effective doubling ofcommunication traffic capabilities.

In order to simplify the disclosure, duplex and diversity channels for asingle PRU are described for a single carrier frequency configuration inFIG. 14. It is understood that a PRU can be controlled to operate atdifferent carrier frequencies, but a single carrier frequency at a time.In single carrier mode the service provider need only install one PRUfor each sector. PRU-A 110 has two antennas: a duplex antenna (DX) 200and a diversity antenna (RX) 210. The DX antenna 200 is shared bytransmitter circuitry 212 and duplex receiver circuitry 214. Thetransmitter 212 transmits at an operating frequency T1. Both receiversDX and RX will down convert a received signal to received frequency R1.Preferably T1 and R1 frequencies have a frequency separation, which isdependant on the frequency band of form a frequency pair. The sector 2and sector 3 PRUs are substantially the same as PRU-A 110. Note that thetransmitter circuitry 212 and the duplex receiver circuitry 214 sharethe DX 200 antenna.

The diversity antenna 210 is in no way connected to the transmittercircuitry 212. Received signals come in the diversity antenna 210 andare provided to the diversity receiver 216. The duplex and diversityreceived signals are combined in the PMU 218 to improve the carrier tonoise ratio (and/or Eb/No). This combining of signals helps negate theeffects of fading and multipath found in the received signals.

The combination of PRU-A 110, PRU-B, and PRU-C cover three sectors or360° about a cell tower. It is understood that a single PRU 110 could beused in an omni-directional mode such that there would be two omniantennas, one for DX 200 and one for RX 210. FIG. 14 discloses anexemplary embodiment of the present invention that provides a PRU 110for transmitting and receiving a communication signal and further have adiversity receiver which reduces degradation effects of fading andmulti-path signals.

FIG. 15 depicts another exemplary embodiment of the present invention.Here an exemplary dual carrier frequency 3-sector configuration for aCDMA transmitter/receiver is shown wherein only two antennas arerequired and diversity reception is still maintained. It is understoodthat various protocols, or power levels can be supported as discussedabove. The additional requirement for a dual carrier mode for eachsector over a single carrier mode in each sector requires an additionalPRU per sector and an additional PMU for the site location. Noadditional antennas are required.

The DX antenna 200 is shared by both transmitter circuitry 212A, theduplex receiver 214A in PRU-A 110A and the diversity receiver 216B inPRU-B 110B. The RX antenna 210 is shared by the transmitter 212B, theduplex receiver 214B found in PRU-B 110B and the diversity receiver 216Ain PRU-A 110A.

Each signal after entering the duplex receiver (214A, 214B) is split bya power splitter (see FIG. 16) such that substantially half the signalis provided to the diversity receiver in the other PRU. Morespecifically, the signal to duplex receiver A 214A is split by a 3 dBpower splitter. One output of the splitter is provided to the duplexreceiver A 214A and the second output of the splitter is provided todiversity receiver B 216B found in PRU B 110B. The duplex receiversignal in PRU B 110B is split in the same fashion as that just describedin PRU A 110A. PRU A 110A will operate at frequency pair #1 and PRU Bwill operate at frequency pair #2. The signal from the DX antenna 200which is split and provided to duplex receiver A 214A is processed bythe duplex receiver A 214A and becomes the duplex signal for frequencypair #1 (DXA1). The signal from the RX antenna which is provided to PRUB 110B is split in the duplex receiver B 214B and provided to thediversity receiver A 216A of PRU A 110A. Thus, the signals processed induplex receiver A 214A and diversity receiver A 216A are substantiallythe same as those found in the single carrier mode, where the DX antenna200 provides signal to the duplex receiver A 214A and the RX antenna 210provides a signal to the diversity receiver 216A. Thus, the outputs DXA1and RXA1 and the signal being transmitted by transmitter A 212A are toall associated with the same frequency pair #1. RXA1 is the diversitysignal associated with DXA1.

With respect to PRU B 110B, it utilizes the RX antenna 210 fortransmitting the transmit signal for frequency pair #2 via transmitter B212B. Furthermore, a signal received from the RX antenna is split suchthat 3 dB of the signal is provided to the duplex receiver B 214B and 3dB of the signal is provided to diversity receiver A 216A. Thus,separate antennas are being utilized for the received duplex anddiversity receivers. Furthermore, the second frequency pair is beingtransmitted and received by PRU B 110B. Output signals RXB2 and DXB2 canbe provided to PMU B via the associated cable as the diversity andduplex signals.

Receive diversity is maintained as both PRUs (A&B) provide independentreceive signals back to their respective PMUs. The advantage with thisexemplary configuration in that capacity is doubled as there are now twofrequencies being utilized. Most importantly, the doubling of capacityis accomplished without installing additional antennas. Further, nohardware reconfiguration is required inside the PRUs. An additionaladvantage is the savings in non-recurring engineering costs and set-upcosts due to the expansion to ability provided by this exemplaryembodiment. Minor exterior cabling modifications may be required to thePRUs to achieve the dual carrier configuration. Note that sectors 2 and3 can be configured in a similar fashion as sector 1 in this embodiment.

FIG. 16 is a high level schematic representation of the duplex anddiversity receiver channels. One can discern from FIG. 16 that thesereceivers can be configured for either a single or dual carrierfrequency configuration. It is understood that FIG. 16 does not includeall the circuitry required, but instead is a schematic block diagramthat discloses the fundamentals of an exemplary embodiment of thepresent invention understandable by one of ordinary skill in the art.

FIG. 16 is divided into a duplex receiver portion and a diversityreceiver portion which are found within an exemplary PRU 110. Looking atthe duplex portion of the drawing, the duplex antenna 200 receives asignal and provides it to a receiver gain stage 300. The signal is thenprovided to an RF splitter 302. The RF splitter is preferably a 3 dBpower splitter. A portion of the signal proceeds to attenuator 1 304 andthen to another receiver gain stage 306. The signal output from thereceiver gain stage 306 is then downconverted and provided as thereceived duplex signal (RxIF_DUP).

If the PRU is set up for a dual carrier wherein two PRU are in use, aportion of the signal is output from the RF splitter 302 to anattenuator 308, the output of which would be provided as an input to theother PRU.

Referring to the diversity portion of exemplary PRU in FIG. 16, when thePRU is configured for single carrier frequency processing, an RF signalis received by the diversity antenna and provided to a receive gainstages section 310. The signal is then provided to an attenuator 311 andthen to a single pole double throw (SPDT) switch 312. The SPDT switch312 is controlled by amplifier bias and switch control circuitry 314which in turn is controlled by the associated PMU.

When the SPDT switch 314 is in position “1” the signal is sent, inessence, from the diversity antenna 210 through the SPDT switch 312 andto another gain stage portion 316. The signal is then sent, via a mixer318, to IF circuitry in the diversity receiver portion in the PRU andthen finally to the PMU.

Conversely, if the exemplary PRU is in a dual carrier frequency mode,the diversity antenna 210, gain stage 310, and attenuator 311 are notused. Instead the diversity signal is received from the other PRU unit.(See FIG. 15) The signal is received at the SPDT switch 312 on pole 2and then provided to the gain stage 316, the mixer 318 and finallyprovided to the appropriate PMU (as RXIF_DIV).

FIGS. 17(a-e) depict a plurality of exemplary embodiment configurationsfor the present invention. FIG. 17(a) is an omni mode, single frequencyconfiguration setup with a diversity antenna. The PRU has two antennasone for duplex and one for diversity. The PRU is connected to the PMU.The PMU may have, a global positioning system (GPS) antenna connected toit.

FIG. 17(b) depicts an omni setup or single sector setup with two PRUssuch that the system is operating with two carrier frequencies with twoantennas one for diversity and the other for duplex. The PMU here can beeither two PMUs or one PMU that handles two frequencies.

FIG. 17(c) depicts an omni, three carrier system with diversity thatrequires only four antennas. FIG. 17(d) depicts a three-sector, singlefrequency system with no antenna sharing. This system maintains bothduplex and diversity reception for each sector.

FIG. 17(e) depicts an omni, six-carrier frequency system with antennasharing. Thus, six carrier frequencies are handled with diversityreception with six receive/transmit antennas.

Thus, the exemplary embodiments disclose a PRU device that can beconnected to handle one or two carrier frequencies without increasingantenna requirements. The present invention allows a service provider toupgrade a cellular (PCS) communication system from a single to a dualcarrier frequency by only requiring the addition of a PRU and a cablingchange. No new antenna(s) needs to be installed on a tower. No changesin technology or re-engineering cost are required. The result is twicethe cellular (PCS) communication capacity without the addition ofunsightly antennas. Basically a service provider buys another PRU, hangsthe PRU on the existing antenna tower, then recables the externalcabling to achieve double the communication capacity. This is a majoradvancement in cellular (PCS) technology and upgradability.

While the invention has been particularly shown and described withreference to specific embodiments thereof, it will be understood bythose skilled in the art that various changes in form and detail may bemade thereto, and that other embodiments of the present invention,beyond embodiments specifically described herein, may be made orpracticed without departing from the spirit and scope of the presentinvention as limited solely by the appended claims.

What is claimed is:
 1. A base station transceiver system divided suchthat a main unit is positioned distally from at least one radio unit,said base station transceiver system comprising: a first radio unitcomprising; a first variable power amplifier for providing amplifiedtransmit signals to a first antenna; a first transceiver circuitryconnected to said first variable power amplifier; and a first controllercircuit electrically connected to said first transceiver circuitry andto said first variable power amplifier; a main unit being for connectingsaid base station transceiver to a land line telecommunication systemand for providing one of an intermediate frequency and base bandtelecommunication signals to said first radio unit, said main unitcomprising a controller circuit for downloading a radio unit software tosaid first radio unit to be reconfigured in response to control signalsreceived from said land line telecommunication system by said main unit.2. The base station transceiver system of claim 1, wherein said at leastone predetermined aspect of said first radio unit is a configurationaspect.
 3. The base station transceiver system of claim 1, wherein saidat least one predetermined aspect of said first radio unit is an alarmconfiguration aspect.
 4. The base station transceiver system of claim 1,wherein said at least one predetermined aspect of said first radio unitis at least one of a transmit attenuation control and a transmit powercontrol configuration aspect.
 5. The base station transceiver system ofclaim 1, wherein said at least one predetermined aspect of said firstradio unit is setting the transmit power of said variable poweramplifier to one of a plurality of power settings.
 6. The base stationtransceiver system of claim 1, further comprising: a second radio unitcomprising: a second variable power amplifier for providing amplifiedtransmit signals to a second antenna; a second transceiver circuitryconnected to said second variable power amplifier; and a secondcontroller circuit electrically connected to said second transceivercircuitry and to said second variable power amplifier, said main unitproviding base band telecommunication signals to said second radio unitand providing control signals to said second radio unit, said controllercircuit further for downloading said radio unit software to said secondradio unit, said second radio unit being configured by said radio unitsoftware such that said second radio unit is configured differently thansaid first radio unit.
 7. A base station transceiver system for awireless telecommunication system, said base station transceiver systemcomprising: a main unit; a first radio unit in communication with anddistally located from said main unit, and a second radio unit incommunication with and distally located from said main unit, said mainunit comprising a controller circuit for downloading a radio unitsoftware to at least one of said first radio unit and said second radiounit to be reprogrammed in response to control signals received from anetwork operating center by said main unit.
 8. The base stationtransceiver system for a wireless telecommunication system of claim 7,wherein said first radio unit and said second radio unit can bereprogrammed to operate differently from each other.
 9. The base stationtransceiver system for a wireless telecommunication system of claim 7,wherein said main unit can request predetermined status information fromeither said first radio unit and said second radio unit.
 10. The basestation transceiver system for a wireless telecommunication system ofclaim 9, wherein said main unit is adapted to forward said predeterminedstatus information to said network operating center.
 11. The basestation transceiver system for a wireless telecommunication system ofclaim 7, wherein a first command can be sent from said main unit to saidfirst radio unit such that said first radio unit responds to said firstcommand by changing an operational aspect of said radio unit.
 12. Thebase station transceiver system for a wireless telecommunication systemof claim 7, wherein a first command can be sent from said main unit tosaid first radio unit such that said first radio unit responds to saidfirst command by providing a status information to said main unit.
 13. Aremotely programmable base station transceiver system for a wirelesstelecommunication system, said remotely programmable base stationtransceiver system comprising: an operations control center; a basestation communication transceiver in communication with said operationscontrol center, said base station communication transceiver comprising:a main unit adapted to receive commands and radio unit software fromsaid operations control center; and a first radio unit, distally locatedfrom and in communication with said main unit, adapted to be configuredwith said radio unit software, said radio unit being for transmittingand receiving wireless telecommunication signals with a wirelesscommunication network, said operations control center being able to settransmit variables of said radio unit via said main unit.
 14. Theremotely programmable base station transceiver system for a wirelesstelecommunication system of claim 13, wherein said operations controlcenter can further request status information from said radio unit. 15.The remotely programmable base station transceiver system for a wirelesstelecommunication system of claim 14, wherein said status informationincludes at least one of an alarm status, a temperature status, areceiver signal strength information, a software version status, and atransmit power level request.
 16. The remotely programmable base stationtransceiver system for a wireless telecommunication system of claim 13,wherein said transmit variable includes at least one of transmit power,transmit attenuation, transmit frequency, and radio unit alarm functionsettings.
 17. A method of upgrading a base station transceiver systemdivided such that a main unit is positioned distally from at least oneradio unit, the method comprising the steps of: providing one of anintermediate frequency and base band telecommunication signals from themain unit to at least one radio unit; downloading a radio unit softwarefrom the main unit to the at least one radio unit; and in response toreceipt of control signals received from the main unit, reconfiguring atleast one predetermined aspect of the first radio unit.
 18. The methodof upgrading a base station transceiver system as set forth in claim 17wherein the step of reconfiguring is further performed in response tocontrol signals received from a land line telecommunication system bythe main unit.
 19. The method of upgrading a base station transceiversystem as set forth in claim 17 wherein the at least one predeterminedaspect of the first radio unit is a configuration aspect.
 20. The methodof upgrading a base station transceiver system as set forth in claim 17wherein the at least one predetermined aspect of the first radio unit isan alarm configuration aspect.
 21. The method of upgrading a basestation transceiver system as set forth in claim 17 wherein the at leastone predetermined aspect of the first radio unit is at least one of atransmit attenuation control configuration aspect and a transmit powercontrol configuration aspect.
 22. The method of upgrading a base stationtransceiver system as set forth in claim 17 wherein the at least onepredetermined aspect of the first radio unit is setting the transmitpower of a variable power amplifier to one of a plurality of settings.